1. Field of the Invention
This invention relates to a system for discharging solid residues of thermal decomposition, and more particularly to a system for classifying and cooling thermal decomposition residues after separation of gaseous and solid products resulting from pyrolytic treatment of city and industrial refuse from dry distillation or pyrolysis or other chemical processes.
2. Description of the Prior Art
The method which has heretofore been utilized most widely in cooling and discharging a thermal decomposition residue is to send the same out of a system by a chain conveyor or like transfer means after dropping the residue directly into water or after water-spraying. Such a discharge system requires the treatment of waste water, and, in a case where it is intended to utilize the recovered residue, there arise problems in that the quality of the residue is deteriorated by moisture absorption and needs a redrying treatment. Therefore, in a situation where the residue is to be recycled, for example, in a case where carbon is recovered after thermal decomposition of waste tires, it is necessary to cool and discharge the residue in a dry condition, in addition to the problem of sealing off a combustible gas atmosphere from which the residue is to be separated at high temperatures. Besides, there arises the necessity for providing some measure to ensure smooth discharge when the residue has adhesive properties or when it is irregular in shape and size and contains foreign matter.
In this connection, it has been known to use a double shaft screw conveyor for a rotary kiln, cooling the residue while it is transferred and discharged by a screw conveyer with a pair of intermeshed tandem screws which are provided with axial passages for circulation of cooling water therethrough. The screws in the tandem screw type discharge system are disposed parallel with each other and supported at opposite ends, so that the discharging operation is often deadlocked by malfunctioning of the discharging ends of the screws.
Especially, when handling residues resulting from thermal decomposition of waste tires, the steel cords and steel beads which migrate into masses of globular form within the rotary kiln are likely to cause malfunctioning or damage of the screws by getting inbetween the two screws or entwining around them at the discharging ends thereof. In some cases, the steel balls within the rotary kiln are connected in long chains which cause malfunctioning to discharge machine components such as a multiple dumper.